Role of calcium channels in the protective effect of hydrogen sulfide in rat cardiomyoblasts.

BACKGROUND Hydrogen sulfide contributes to the reduction of oxidative stress-related injury in cardiomyocytes but the underlying mechanism is still unclear. AIMS Here we investigated the role of voltage-operated calcium channels (VOCCs) as mediators of the beneficial effect of H2S against oxidative stress in cultured rat cardiomyoblasts (H9c2). METHODS Intracellular calcium signals were measured by fluorimetric live cell imaging and cell viability by colorimetric assay. RESULTS Treatment with H2S donor (NaHS 10 µM) or Nifedipine (10 µM) decreased resting intracellular calcium concentration [Ca]i, suggesting that L-type VOCCs are negatively modulated by H2S. In the presence of Nifedipine H2S was still able to lower [Ca]i, while co-incubation with Nifedipine and Ni(2+) 100 µM completely prevented H2S-dependent [Ca]i decrease, suggesting that both L-type and T-type VOCCs are inhibited by H2S. In addition, in the same experimental conditions, H2S triggered a slow increase of [Ca]i whose molecular nature remains to be clarified. Pretreatment of H9c2 with NaHS (10 µM) significantly prevented cell death induced by H2O2. This effect was mimicked by pretreatment with L-Type calcium channel inhibitor Nifedipine (10 µM). CONCLUSIONS The data provide the first evidence that H2S protects rat cardiomyoblasts against oxidative challenge through the inhibition of L-type calcium channels.